Linear fluorescent lamps have been the light source of choice for commercial applications, to include signage, in the United States and other countries for much of the twentieth century. The many types of linear fluorescent lamps currently range from a nominal size of less than one foot to a nominal size of ten feet. Because of the many standard sizes of linear fluorescent lamps in commercial lighting, commercial signage is designed around the nominal length of the linear fluorescent lamps.
In commercial signage, linear fluorescent lamps are often mounted in a parallel fashion in what is known in the industry as cabinet signs. The structure of the interior of the prior art cabinet signs provides mounting points, typically the two fluorescent lamp sockets, between which each linear fluorescent lamp is placed. The two sockets both hold the linear fluorescent lamps in position and enable a female electrical connection to the prongs which extend outwardly from the ends of the linear fluorescent lamps. To accommodate small variations in the lengths of linear fluorescent lamps, one of the sockets, typically the socket at the top of the cabinet sign, includes a spring to assure that the linear fluorescent lamp is held in place and that a suitable electrical connection is established.
While it is generally cheaper to operate linear fluorescent lamps than the incandescent light bulbs that linear fluorescent lamps replaced, the continuing increases in the cost of electrical energy have resulted in the need for a source of light energy that is cheaper to operate and more reliable than linear fluorescent lamps.
Several decades ago LEDs became available as a lighting source. Initially, the low light output of LEDs limited their use to indicator lights typically used with electronic control systems. Since the initial introduction of LEDs their output of light energy has increased to where the light output of LEDs rivals the light output of both incandescent light bulbs and linear fluorescent lamps. In addition to being less expensive to operate than linear fluorescent lamps, LEDs have a much longer life; thus, the operational cost of LEDs per unit of time is much less than systems using conventional linear fluorescent lamps.
LEDs also provide other features not found in systems using linear fluorescent lamps. Those features include color and flexibility. Most linear fluorescent lamps emit white or off-white illumination. LEDs emit light in multiple colors. Further, LEDs are typically provided in modules, which LED modules are connected one to another by wires. Thus, for commercial lighting designers, LEDs provide more flexibility and less cost over time.
Since fluorescent lighting has been around for more than half a century there are many cabinet signs designed for fluorescent lamps which are still serviceable and will remain serviceable for many years to come. Rather than building entirely new signage structures for the use of LED lights, the need has developed in commercial lighting applications for a system and method to replace linear fluorescent lamps with LED modules in existing prior art cabinet signs designed and built for the mounting of linear fluorescent lamps.